Pyro-electric furnace.



PATBNTED DBG. igfisos-' E. C .vi vw. .Dn HU GDL A 0m RDM .T BC .m FE O R VL D...

PATBNTED DEG. 18, 190s.

. B. Roma.

PYRO ELECTRIC PURNACB.

APPLIGATXON FILED CLl. 1905.

6 SHEETS-SHEET 2.

C l/TLU@ 732502/j PATEHTED DEC. 18, 1905.

4 F. E. ROACH.`

PYRO ELECTRIC FURNACE.

APPLICATION FILED OOTJI. 1905. Y

5 SHEETS-SHEET 3.

, PATENTED DEG. 1 8, 1906.

P. E; ROAGH. PYR ELECTRIC FURNACE..

APPLICATION FILED 00111. 1905.

5 SHEETS-SHEET 4.

, PATENTED DEQ-18, 1906.

P. E. ROAGH..

I PYB@ ELECTRIC PURNAGB.

APPLICATION FILED 0-GT.11, 1905.

5 SHEETS-SHEET 5.A

u Wwac:

UNITED STATES Fl-NIS E. ROACH, OF CHICAGO, ILLINOIS.

FYFlO-ELECTFZIC FURNACE- A Specification of Letters Patent..

Patented Dec. 118, 1,906.

Anvlication fled October 11, 1905. Serial No. 282,272.

T0 all whom, it may concern:

Be it known that I, FINIs E. Rosen, a citizen of the Unit-ed States, and a resident of Chicago, Cook county, Illinois, have invented certain new and useful Improvements in Pyro-Electric Furnaces; and I doherebydeelare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, and to the letters of reference marked tiereon, which form Va part of this specification.

This invention relates to improvements in pyro-electric furnaces, and is shown more particularly embodied as a' dental furnace fot` the baking of porcelain and similar material,` though obviously it lmay be used for many different purposes for heating or bakinftmaterials of any kind..

In furnaces heretofore devised for dental use ai considerable portion of heat has not been utilized, because it has been necessary to provid can opening in one side or one end or in the op of the furnace to permit the operation of the furnace to be carefully Watched by the operator,\or if a closed furnace it has heretofore been necessary to frequently open or partly open the furnace to inspect the process of baking. In either case the material is exposed to a draft of air injurious to the niaterial and permitting a large loss of heat either through the view-aperture or While the furnace is open for purpose of inspection. Though attempts have been made in the past to apply mechanical devices for regulating the heat, it has been, nevertheless@ eessary for ti. trained operator to give the Work careful attention to prevent inuring material treated, for the reason that large ni es of material treated requirclongerperiod of time and much more heat than smaller masses, anti it has heretofore been very di'icult, if not impossible, to adjust a furnace quickly to the heat required for a given material or for varying quantities of the material.

The object of this invention is to afford an 'electric furnace in which the material treated is at all times wholl)T inclosed in the furnace unil, subjected to a high temperature, gradually increasing to a preetermined maximum duringt a predetermined time.

It. is also an object of the invention` to af ford mechanism whereby the furn can he set to afford is a maximum any t. ired degree of heat v ithin the range of the furnace and adapted when said degree of heet has been attained to break the circuit, permitting cooling.

The invention has also for its object a con struction in which material treated is positively supported at approximately the cenoo ter of the furnace, at the point of maximum heat.

It is also an object of the invention to so construct the furnace as to enable the heat to be applied instantaneously and uniformly to all parts of the article heated, or the bake, during the entire period of heating and in which at a predetermined temperature the current will cease.

A further object of the invention is to af- 7o ford a construction in which the pyrometer can be quickly set to insure either a quick bake or a slower bake.V

It is a further object ofthe invention to construct an automatically-operating furnace in which the parts can be quickly assembled or as quickly separated and in which the heating element or inutile of the furnace can be lifted from the furnace.

The invention embraces many novel fea- 8o tures; and it consists in the matters hereinafter described, and more fully pointed out and defined in the appended claims.

. lIn the drawings, Figure 1 is a side elevation of a furnace embodying my invention. Fig. 2 is a vertical section thereof. Fin. 3 is a section taken online 3 3 of Fig. 2. Fig. 4 is an enlarged fragment-ary front elevation of a part of the pyrometer. Fig. 5 is a side elevation of the carrier for the thermostatic 9o slug. Fig. 6 is a section taken on line 6 6 of Fig. 4. Fig. 7 is a longitudinal section of the carrying-sleeve. Fig. S is a side elevation of the thermostatic slug. vat-ion of the muflle. vation of the outer casing for the inutile. Fig. I 1 is an enlarged fragmentary section of the inutile., showing the crimping of theoresistanCeWire- Fig. I2 is a View of the coverbase of the furnace with the yrometer rerco moved, showing the side rods roken. Fig. 13 is a longitudinal section of one ofthe separahle binding-posts- Fig. 14 is a fragmen tary side elevation ofaone of the cont-acts therefor. Fig. 15 is asection taken on line m5 15 1:3 of Fig. 13. Fig. 16 is"a\section taken on line 16 16 of Fie'. I3. Fig. l7\is\a side elevation, partly brolzen, showing theeu of die furnace lifted from the furnace-base r-.uldsupi ported on the insulatbig-base. Fig. .8 is a no Fig. 9 is a view in ele- Fig. I() 1s a similar ele- 95 eeaca'z pan shown in Fig. 17. Fig. i9 is a similar view showing a flat plate used in lieu of the pan. F ig. 2O is a fragmentary side elevation of the same. elevation illustrating a preferred form of ad.- justing mechanism for the pyrometer. Fig. .22 is a section taken on line 22 22 of Fig. 21.

A :3 shoppin the drawings,A indicates an insulating-hase of slate or any suitable material. Secured thereon are upright parallel tubes a, one' on each side of the center, as

shown in Fig. 1 and in dotted lines in'Fig. 3. These serve as standards to su port lthe fur nace, (indicated as a whole as l.) The base B of said furnace is rigidly secured upon said tubes A or. standards a', which open therethrough, as shown in Figs. 18 and 19, and comprises an annular plate of metal or any suitable material secured thereon and acentral upwardly-tapering tablet b, of refractory and non-conducting material, such' as lire-clay, asbestos, or any suitable material. A ccntral aperture is provided through the furnacebase and through said tablet, and rigidly secured therein is a cylindric sleeve which extends downwardly for a considerable distance below the bottom of the furnace and is longitudinally slotted in its iront side and peripherally slitted, as shown in Fig. 4, to afford relatively short 'supporting-fingers c, adjacent each of which arev marked numbers or characters, as shown l to 10, inclusive, which indicate the baking temperature of different lrinds of material to be treated or the duration of the treatment or the relative length of time during which the material is subjected to heat. Slidably secured in said graduated sleeve C is a tubular carrier having on one side'of the same a finger c2, adapted to project through the slot in the sleeve and to v e supported on the fingers c. The upper end of said carrier-tube c is adapted to be projected above the base of the furnace and is provided With a tubular tip c5, which may be made of metal or of any refractory material and which, as shown, is provided near its upper end with an internal flange c, above ch the bore in the end of the tip is enlarged. ,The head of the fusible slug c5 is supported on the ilange c in said tubular tip. Said furnace-base B' is provided with relatively large apertures therethrough on the rear side thereof, (indicated by 62,) beneath which and rigidly secured to the insulatingbase A are metallic bindingosts D, each provided with a cylindric soc et in its top and split longitudinally to aiiord resiliency.

Pivoted on e post d3 is a lever D2, the forward' end of which extends beneath the split sleeve or tube C or C' and is expanded to form a pan d. The rear end of said lever is provided with a downturned flange di, adapted to be engaged by the end of a leaf-spring d, also secured on the insulating-base A. A con- Fig. 21 is a fragmentary front fords a support for the muiiie.

dnctor d leads from one of said binding-posts D to an ordinary bindingost D'. A conductor-Wire d" leeds from t e pt-her bindingpost D to the post d5, on which said lever 1s pivoted, and a conductor-Wire d connects the spring d with an ordinary bindingost Dit," secured on the. insulating-base A. aid

binding-posts D' D: are adapted forc'onnece.

tion with the source of current-supply.

The furnace proper, or that part containing the inutile, comprises a metallic shell Bhaving secured therein at its bottom a late B, of metal or any Sait able material, aving a central a erture therethrough of a size to receive andlfit aro-rnd the central conical tablet b, as shown in Fig. 2, and which rests flat upon the furnace-base B. The upper end or top of the she-il B2 is closed by means of a metallic plate B4, rigidly secured thereto, and atthe center of winch is a projection B, having an aperture therethrough, rvhereby the furnace can be lifted from the furnace-base.

Within the fornace and supported on the annular bottoni plate B3 is an annular sup- -port or bottom E) of fire-clay, asbestos, or other suitable reiiactory and insulating material, and which projects inwardly partl over the tablet as shown F'g. 2, and a A baid mufiie, as shown, comprises a thin upwardly-tapering shell E', of insulating and refractory material-such as porcelain, tire-clay, or anyx suitable material-open atboth ends and provided at its `vor-er and loneredges with closely-arranged serrations, between which and Wound ar t; d and through the shell is the resistance-vire e.

Preferably this wire is provided with a plurality of crinips, as shown in Fig. 11, at each bend as the same is passed through around the inutile and engages in the nerehes at each end thereof thus increasing terially the quantity oi wire and obvisting any possible tendency to breakage due to expansion and contraction. As shown, said s l E', forming the inutile is split on one s` apertures are provided, one on each side of said slit near. the bottom of the shell and through which the ends of the conductor- Wires e are passes. einen the Winding is cornpleted, thus preventing short circuiting where the Wires enter and leave the Inutile. Said muiiie is si, ported upon a ledge of the insulating-suppe E, and over the same is secured a shell or csp E2, of porcelain or any suitable materi i, ont of Contact therewith, but fitting closely thereto. Said shell lor cup is provided with siots at ti i bottom of the same, through which the ends of the resistance wire pass from the inutile, after which said ends are carried upwardly over. the cup, as shown Fig. 3, and downwardly on the other side and inserted into a slot in the posts F, which, shown, are tiro in number, positioned to project through the large 4the shell El5 and a ertures in the base and register with the bmdino posts D, before described. Said osts l* are rigidly secured on the metallic )ot-tom B3 of t e furnace by means of an insulating-bushing f, which lits in suitable apertures in said annular' bottom plate B3 and into which the osts F are screw-tlueaded. Engaged on eac i are binding-nuts f and fl, between which the ends of the wires are turned outwardly from the ends of the slot.. rl`he lower ends of said posts l" are t-a lered at their extremity to fit into the socket-s at the upper end of the split binding-posts.

The furnace-casing is lilled with asbestos or any suitable non-comluctive material, (indicated by B,) which is closely packed about aids in holding the saine in p lace and also prevents loss of heat. by radiation.

Supported on standards gon the tablet l), which affords a closed bottom for the mufiie, is a tray G. Said tray may be constructed of a pan having upturned e ges` and in which the article to be treated is placed, or it may be constructed as asimple plate, (indicated by G' in. Fig.'19.)

As shown, standards or legs H are provided on each side of th'e furnace, secured rigidly to the annular bottom plat-e B and registeringr with the tubular standards a. A and when the furnace is seated upon the furnace-base fit therein and hold the saine in place. The lower ends h of said standards or legs H are of smaller size and fit in suitable sockets h' in the insulating-base A, as shown in Fig. 17.

thus supporting the furnace when removedfrom the baseB,or the same maybe supported in the sockets hz in'said furnace-basa."

4 As shown in Fig. 21, the tube or split sleeve C is constructed as before described, except that the peripheral slots and lingers are omitted and a lever K is pivoted on one of the standards a by means ofa ring k, secured on the standard and having a flat face, against which the end of said lever is engaged by a screw lf2-and washer c. The free end of said leve'.` is adapted for adjustment alone' the opposite standard A, which is -graduated to correspond with the grade. or th'e baking temperature of the material treated. Said tongue c2 on the pyroineter or thermostat rests on said lever, so that movement of the lever produces correspondingr adjustment of the same.

The operation is as follows: With the bake or article to be treated supported upon the tray G or G approximately at the center of the inutile, where the temperature is highest, the inutile is placed upon the furnace-base B', with the legs or standards H tilting into the tubular standards 1 A3. The reduced and tapered endsf3 of the posts F engage in the sockets at the upper ends of the binding-posts I), as shown in Figs. 2 and 13, and are firmly clamped between the resilient ends of said posts. In' this position the mutlle is entirely closed and is held very securely upon the base B', with the tablet b partly within the insulating and spacin ring E. Before closing the furnace a slug'o metalas, for instance., leadwhich may be conveniently shaped, as shown in Fig. 8, to allord a peripheral flange at its upper end, is dropped into the upper end of the tubular carrier c3 vand is supported therein with its head in the couutcrsunk end of said ear-l rier. The carrier is now adjusted as to height by means of a lever before described or on the. graduated lingers c to correspond with the character of material or the degree of temperature to be. attained in the furnace to perform the required operation. If Va relatively low temperature is to be maintained for a short time, the slug is elevated, as shown in Fig. 2, to a point where it receives practically the maximum heat of the furnace, and if a higher temperature is to be applied to the ob'cct treatedn the slug is adjusted downwardly to the point where it is in part protected from the heat thereof by the surrounding walls. lt is 'obvious that with the slug adjusted to a point below the tloor of the furnace the time required to melt the slug will be much greater than when adjusted into the mu'lllc and also that a greater degree of heat is received at the middle of the furnace than at any (part of the furnace intermediate theA same an It follows that by means of the thermostat or pyrometer aliordcd by the construction described the degree of heat and its duration can be determined by the position of the slue', which may be either a high or low fusing metal. The current lowingthrough the lever D2 as one of the conductors is in stantly broken by the fall of said metal through the carrier and sleeve into the pan d, which strikes said end of the lover downwardly, releasing the spring, thus breaking the circuit. The furnace, with the bake tlterein, may then be reducing the temperature slowly and avoiding any tendency toward cracking by sudden contraction, or the furnace may be lifted from the furnace-base and the reduced ends 7i of the legs or standards inserted in the sockets 7i at the rear of the insulating-base, as shown in Fig. 7, thus supporting the same in upright position, or, if preferred, the reduced ends of said legs may be inserted in apertures in the furnacebase B', thus holding the same in upright position.

Obviously during the entire operation of the furnace tle bake is iositioned centrally within a inutile in whicli, beingl wound on both the inner and outer side, the maximum heat elliciency is attained. Furthermore, should a resistance-wire break all partsof the furnace. are quickly accessible, and it is only necessary to twist the broken ends of the the floor...

allowed to cool, thus- .los

IIO

wire together to restore the furnace to o erative condition. This can usually be one by reaching into the muflle from the bottom, or, if preferred, the top plate B* and the packing may be removed andrthemuiigrernoved from the casing. i

lVhile I have described the furnace as cylindrical in form, it is obvious that other forms may be employed, and of course other forms of bindin -posts, enabling the furnace to be quickly etached from the base B. Obviously many details of construction may be varied, and I therefore do not purpose limiting this application for patent otherwise than necessitated by the prior art.

I claim as my invention- 1. In a furnace the combination with a base of an inclosed inufiie fitted upon the` same and wholly closed thereby, means for heating the mul-lle and heat-regulating means therefor, said furnace being opened by lifting the muile' from itsbase.

-2. An electrical furnace comprising a base of refractory material and binding-posts, an inclosed muflle adapted to t upon and to be entirely closed by said base and posts electrically connected with the mufi'le and adapted for sliding engagement with said bindingposts when the inuffle is closed by the base.

3. An electrical furnace comprising a furnace-base, a inutile closed at the top and sides fitted thereon and completely closed thereby, electrical contacts adapted for sliding engagement one with the other, adapted to complete the circuit and thermostatic means acting to limit both the tem )erature of the furnace and the duration of t e bake.

4. In a device of the class described, an inclosed muflle comprisingr an annular, split shell and resistance-wires around the inner and the outer'side thereof, and having their ends extending therefrom at each side of the s' lit.

p5. In an electrical furnace, a inutile comprising f1 siit sleeve or shell having its edges :notched at -each end and a resistance-wire ing at the turns crimped to aiord a plurality of bends at the upper and lower edge of the shell.

Y. In a device of the class described a muflle comprising a tapered open-ended longitudinally-split shell of refractory and non-conducting 'material having closely-arranged i acting to ruin ofi the heae l) v D n notches et each end thereof, a resistance-wire wound continuously around the inner and outer side of the shell the turns engaging in .said notches and crimped each turn to afford a plurality of bends, `the ends of said wire extending through apertures in said shell on oppo "e sides of the slit and a casing of non-conducting and refracory material inclosing the tcp and sides of the muiile.

8. ian a device of the class described amufile comprising a tapered open-ended longitudinally-split shell of refractory and non-conducting rnaterial having closely-arranged notches si. each end thereof, a resistance-wire wound continuously around the inner and outer side of the shell the turns engaging in said notches and crimped at each turn to afford. a purality of bends, the ends of said wire extending through apertures on said shell oncpposite sides of the slit and a casing of non-conducting .and refractory material inclosing the top and sides of the Inutile and around rnd over which the ends of the resistance-Wires lead.

9. In sin electrical furnace a muflle comprising annular shell of insulating material open at each end and sl Et longitudinally in one side, a resistancewfire Wound around through and-through the same from one side of the slit` around the sheil the other, and

l the ends thereof passing outwardly through suitable apertures on each cup of refractory materie` and sides of said muflle and bound thereto by the resistance-wires and to converge the heat inwardly and a bottom entirely closing tine niufiie and affording a support for the material treated.

10. nu electric furnace comprising a muffle inclcse-d at ihe lop and s des, a removable close-fitting bottom there i binding-posts rigidly connected with tle n'iuille and with de of the split, a closing the top which tends el the rei -wire are con# nected, `i complementar finding-posts on the lume e-base adapted to engage the same to aiiord e. sliding connection- 1l. elect ric fui nace c ile inclcsed at tlie top and f, a removable close-fitting bottom there. binding-posts rigidly @pnnected with the niufile and with wlicn the ends of the resiste* nected, complementari bin fulnace-bse adapted to er afford a ending connection ically-o Jeral ed means ect circuit at predelermine(i 12. In a furnace the c Ypr is in g a mufg-pcsts on the e the same to 'iper-attire.

lation with a actor-y tablet d at its sides end and adapten to be closed at the bott-,an by said table; iii-conducting packing surroundingthe T e and an adjustable thermostat adap o be set to opcrate at predetermined` perature and amat really.

ICO

13. An electrical furnace com rising an electrically-heated inutile wholly c osed, a removable bottom therefor, a support on the bottom, a pan secured on the bottom and act- 'ing to support the material treated approximately at the center of the muflle, packing material inclosing` said mullle, a thermostat or pyrometer, communicating with the interior of the inutile and adapted for adjustnient to a wide range of temperatures and means connected in the electrical circuit and operated by the thermostat to break the circuit at' temperature for which the thermostat is set.

14. In a device of the class described the combination with s furnace-base of a refractory tablet supported thereon at its middle, an electrically-heat ed Inutile closed at its top and sides and adapted to fit over the insulating refractory tablet on the base, thereby wholly closing the muille, a support on said tablet positioned approximately at the center of the inutile for the material treated, a regulable and graduated thermostat engaged on said base and adapted to break the circuit at a predetermined temperature and standards or legs on the furnace adapted toalford a support therefor clear from the furnacebase. f

15. In a device of tle class described the combination with a mufller of means inclosing the saine, a' resistance-coil in said muffler, a support in the mutller and a vertically-adjustable carrier below said support.

16. in a device of the class described the combination with a inufiler of means inclosing the same, a resistance-coil wound about said muiller, 'electric conductors connected therewith, vert ically-adjustable thermostaticmeans connect ed with said muiller and means operated thereby at a predetermined temperature adapted to brea the circuit.

17. In a device of the class described'the combination with a furnace-base of an annular muffler supported ti ereon, means closing each end of said muliler, .means for -heating said muffler, a sleeve rigidly ,engaged in said bese and o ening upwardly to said mulller and vertically-adlust able means in said sleeve adapted to cut oil' heat at. a predetermined temperature.

18. In a device of the class described the combination with a furnace-base of a mutl'ler carried thereon, means closing the ends of said muller, s. resistance-coil wound about said mutller, conductors connected therewith, a lever normally connected with said conductors and forming part of the circuit, a vertically-adjustable carrier supported in said base and means therein adapted at a predetermined temperature to operate said rever and break the circuit.

19. In e. device of the class described the combination with a furnace-base 'of an inclosed muliler thereon, a resistance-coil on jsaid mulller, posts connected therewith and projecting through said base, an insulatingase and split binding-posts thereon adapted said mutller, an insulating-base ri idlyer1- ygaged to the furnace-base, binding-posts thereon adapted for engagement withv the resistance-coil, a vertically-adjustable carrier in said furnace-base and projecting into' the muiler, a lever carried on the insulatingbase and normally forming .srt of the circuit and fusible means on sai carrier adapted at a redetermined temperature to operate said .ever to break the circuit.

22. In a device of the class described the combination with an' insulating-base of tubular standards thereon, ainrnace-base engaged on said standards and provided with apertures opening thereinto, a tapering tablet on said base, an inclosed muidersupported n thereon a resistance-coil on said mu ner, a

annular bottom plate surrounding said tablet, posts thereon extendin through the base and adapte to receive the ends of said coil therein, split binding-posts on said insulating-base adapted to en age said posts, legs on said annular bottom p ate "adapted to engage in said standards, an

electric circuit connected with said coil and means for breaking the same at a predetermined temperature.

23. In a device of the lclass described the combination with an insulating-base of a downwardly IIO furnace-base supported above the same, an

inclosed mufiler on said furnace-base, a resistance-coil thereon, conductors connected with said coil, a sleeve extendin upwardly through the furnace-base, a hol 0W carrier therein ada ted to contain a fusible slug, means for a justine said carrier with respect to said mu'ler and i insulating-base'and forming part of the circuit and adapted when sai slug is fused to break the circuit.

a lever carried on said 24. In a device of the class described the combination with a furnace-base of a tablet therein, a mudler supported on said tablet, a resistance-coil on said muh'er, means for connecting said coil in an electric circuit, a slotted sleeve engaged in said base and opening to said muller, a hollow carrier adJustabb' engaged in said sleeve, a lnger thereon pmJectlnv through-the slot 1n sald sleeve,

means m apted t o engage said fnver andg hdd the carnet 1n adjusted posltlon and means beneath the sleeve adapted to break the cucult at a predeternuned temperature.

In testlmony whereof I have hereunto subscribed mv name in the presence of two snbi scribing itneei FINIS E. ROUH.

Yitn'essesz v i C. W'. HILLS, i W'. VHHENBURY. 

